A 13-year-old girl scout has shown business savvy way beyond her years - by setting up a cookie stand outside a medical marijuana clinic.

Young genius Danielle Lei, from San Francisco, set up the stall outside the Green Cross marijuana dispensary with help from mum Carol.

According to the dispensary's Facebook page, Danielle sold out of cookies in just 45 minutes - and had to call for extra stock.

In just two hours she'd sold 117 boxes of Tagalongs and Thin Mints, 37 more than she'd sold in the whole of the previous day in a different location.

Carol encourages her daughters to sell cookies in different parts of town to expose them to different walks of life.

But some branches of the Girl Scouts of the United States of America have been less than impressed with Danielle's ingenuity.

The Colorado branch tweeted yesterday:

They went on to clarify that this included "bars, strip clubs, casinos, liquor stores or marijuana dispensaries. We recognise these are legitimate businesses, but we don't feel they are an appropriate place to be selling cookies."